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Refactor elimination of *current* op in optimiser

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The code to handle this was duplicated in two places; this pulls it out
to a common chunk of code triggered by negative values of freeops.

This isn't a big win here, but it sets us up to re-use this code in
later commits.
This commit is contained in:
Steven Flintham 2017-07-28 22:57:46 +01:00
parent 5a2af29fd6
commit 8a672501b7
1 changed files with 30 additions and 21 deletions
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51
src/toolsrc/codegen.c
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@ -913,7 +913,7 @@ void release_seq(t_opseq *seq)
*/
int crunch_seq(t_opseq **seq)
{
t_opseq *opnext, *opnextnext;
t_opseq *opnext, *opnextnext, *opprev = 0;
t_opseq *op = *seq;
int crunched = 0;
int freeops = 0;
@ -977,15 +977,7 @@ int crunch_seq(t_opseq **seq)
break;
case BRFALSE_CODE:
if (op->val)
{
opnextnext = opnext->nextop; // Remove never taken branch
if (op == *seq)
*seq = opnextnext;
opnext->nextop = NULL;
release_seq(op);
opnext = opnextnext;
crunched = 1;
}
freeops = -2; // Remove constant and never taken branch
else
{
op->code = BRNCH_CODE; // Always taken branch
@ -995,15 +987,7 @@ int crunch_seq(t_opseq **seq)
break;
case BRTRUE_CODE:
if (!op->val)
{
opnextnext = opnext->nextop; // Remove never taken branch
if (op == *seq)
*seq = opnextnext;
opnext->nextop = NULL;
release_seq(op);
opnext = opnextnext;
crunched = 1;
}
freeops = -2; // Remove constant never taken branch
else
{
op->code = BRNCH_CODE; // Always taken branch
@ -1206,8 +1190,32 @@ int crunch_seq(t_opseq **seq)
break; // LOGIC_NOT_CODE
}
//
// Free up crunched ops
//
// Free up crunched ops. If freeops is positive we free up that many ops
// *after* op; if it's negative, we free up abs(freeops) ops *starting
// with* op.
if (freeops < 0)
{
freeops = -freeops;
// If op is at the start of the sequence, we treat this as a special
// case.
if (op == *seq)
{
for (; freeops > 0; --freeops)
{
opnext = op->nextop;
release_op(op);
op = *seq = opnext;
}
crunched = 1;
}
// Otherwise we just move op back to point to the previous op and
// let the following loop remove the required number of ops.
else
{
op = opprev;
opnext = op->nextop;
}
}
while (freeops)
{
op->nextop = opnext->nextop;
@ -1217,6 +1225,7 @@ int crunch_seq(t_opseq **seq)
crunched = 1;
freeops--;
}
opprev = op;
op = opnext;
}
return (crunched);